Method of forming set screws



Sept. 20,1927. 1,642,736

c. E. LYMAN METHOD 0F FORMING SET SCREWS Filed May 8. 1926 PatentedSept. 2D, 1927.

UNITED STATESA CHARLES E. LYHAN, F WATERBUB'Y, CONNECTICUT.

METHOD 0F FOBMING SET SCREWS.

Application led lay 8,

This invention relates to a method of making set screws of the type thathave in their heads angular sockets which are adapted to receive a kewrench for turning the screws into and ou of place.

The object of the invention is to prov1de a process by means of whichsuch screws may be produced from cold slugs of metal very rapidly andcheaply, there being few o erations and no waste metal, and the metal othe slugs bein so flowed as to produce dee and accuratey sized andshaped sockets wit strong walls, thus ensuring a good fit for the wrenchand eliminating danger of splitting or breaking the screws or wearing orstretching the sockets so that the wrench will not turn the screws wihenthey are screwed into place tightly, or when it is desired to remove thescrews after they have been in place for a long time and have becomecorroded.

In attaining this object a slu of cold metal of uniform diameter cut t eproper length from a rod or wire is fed into a die cavity of slightlylarger diameter than the diameter of the slug, and while confinedtherein is subjected to percussive force in such manner thatcoincidently a conical cup is formed in one end and the other endextruded from the die\ cavity onto a punch which acts as a mandrel andabout which the extruded metal flows to form the socket, the exteriorofthe slug about the socket during this action being given approximatelfinal shape and size by the contour of the wall at the mouth of the diecavity from which the metal is extruded. The cupped end of this blankthus produced is then bevelled and coincidently the socketed end isrounded, and nally a thread is cut or rolled on the exterior of theblank. By the practice of this process, without heating, strong andaccurate grub set screws can be produced by three operationsor by threemachines only.

The "blank forming step of this process may be taken by such tools asare described in my co-pending application #752,161, filed Nov. 25,1924, although other tools can be employed, and those tools areespecially'q adapted to be used in a solid die cold header of well knowntype, such as is set forth in United States patent to Campbell #569,406,

Oct. 13, 1896 although other heading machines could be used.l

In the accompanying drawing Fig. 1

1926. Serial No. 107,545.

shows a side view and a transverse section of a rod from which aeslugmay be cut. Fig. 2 shows a side view and longitudinal section of theslug. Fig. 3 shows a side view and longitudinal section of the socketedand cupped blank produced from the slug by the first step of theprocess. Fig. 4 shows a side view and longitudinal section of the blankafter it has been rounded and bevelled by the second step. Fig, 5 showsa side view and longitudinal section of the finished set screw, that is,the blank after a thread has been rolled or cut on its exterior. Fig. 6shows a die, feed pin and punch, and thei:l supporting parts of aheading machine, nhich may be used in practicing this invention. Fig. 7is a section of the die with a slug fed into it by a feed pin. Fig. 8 isa section showing the punch or mandrel advanced and about to act upont-he slug in the die. Fig. 9 is a similar view showing the relation ofthe parts after the slug has been percussively acted upon to produce thecup at one end and the socket at the other en In the practice of thisinvention the slugs 1 can be cut from a rod 2 of uniform diameter fedinto a Cold header in the usual manner, or they may be produced inanother machine and fed individually into the header in the well knownway.

In the views 3 indicates the forward end of a punch bed which is mountedon thev reciprocating ram of a header so that it may be raised andlowered for first presenting the feed pin 4 and then the punch 5 in linewith the die 6, and also carried back and forth for feeding the sluginto the die cavity and then for acting upon the slug in the cavity, asis well understood. The feed pin of the tools illustrated is mounted ina thimble 7 set into the punch bed, and is pressed forward by a spring8. The punch is mounted in the punch block 9 set into the punch bed withits forward end supported and guided by a sliding sleeve 10 and its rearend abutting against a hardened backing plate 11. The forward end of thepunch projects a slight distance beyond the front end ofthe unch blockand its cross sectional shape 1s that which will produce the requiredcross sectional shape, preferably hexagonal, of the socket in the screwto be made.

The die is slidably fitted in a sleeve l2 that is secured in the frontwall 13 of the frame of the header. The die cavity has a cross sectionalsha e that will impart the exterior outline to t e screw blank to beproduced, and the die is normally pressed forward by a spring 14.Projecting into the die cavity from the back is a pin 15 attached to theend of the knock-out plunger 16. The length of this,pin is'variedaccording to the length of the slug that is to be operated upon and ithas a conical tip 17 which is desifrned to form a vcup in the bottom endof the slug.

With the parts in their normal positions and doing no work the die ispressed forward by its spring andthe tip of the pin is a short distanceinside of the face of the die, while the forward end of the punch isslightly forward of the face of the punch block, as illustrated in Fig.6. In the standard two-blow cold header for which the tools shown areespecially designed the slug that is slightly smaller in diameter thanthe die cavity is fed inthe usual way and pushed into the die cavity bythe feed pin that at this time is in line with the die. As this takesplace the backing pin and knock-out plunger are forced back asillustrated in i 7. After the feed pin is withdrawn and raised and thepunch brought into line with the die, the punch is driven forward. Asthe punch enters the die opening and engages the slugthe face of thepunch block engages the face of the die and presses the die back. Thedie is forced back a distance equal to the distance the punch is driveninto the slug, and as the slug is held by the backing pin the metal 18displaced by the punch 1s extruded from the die cavity form- 1n aroundthe punch as a mandrel. Fig. 9. with this action the surface of the wall19 at the mouth of the die cavity which controls the exterior shape ofthe metal extruded is always the same.

With the slug confined in the die in this manner and backed by theconically tipped pin, the blow given by the punch produces the elongatedb ank 20 of unlforln diameter, Fig. 3, with the hexagonal socket 21 atone end and the conical cup 22 at the other end. This step of theprocess may be performed by the well known heading machines, and itproduces the required cupped blanks very rapidly and cheaply withaccurate and well formed sockets and exact exterior diameter.

Theseblanks can then be fed to a common screw machine which is tooled toround off `the socketed end 23 and taper the cupped end 24, Fig. 4,which cutting operations may be performed coincidently, after which ation opposite to the movement o-f the unch and die, and subsequentlythreadingt e exterior of the blank thus produced.

2. The method of forming socketed4 set screws which consists in feedinga cold meta-l slug of uniform diameter entirely within a cavity, holdingthe` inner end of the slug in a fixed position, 'forcing a punch ofsmaller diameter into the outer end of the slug thus confined and heldand coincldently retreating the cavity a distance equal to the advanceof the punch into the slug, whereby metal of the slug is caused to flowlongitudinally out of the cavity and along'the punch, and threading theexterior of the blank thus produced.

3. The method of forming socketed set screws which consists in feeding acold metal slug of uniform diameter entirely within a die cavity andwhile the slug 1s confined and `held stationary by percussive forceexercised against the slug, coincidently forming a cup in the inner endof the slug and causing the outer end of the slu to elongate and extrudefrom and be shaped by the mouth of the dier cavity, in a directionopposite to the application of said force and produce a socket in saidelongated end,

and threading the exterior of the blank4 thus produced. .n

4. The method of forming socketed set screws which consists in feeding acold metal slug of uniform diameter entirely within a die cavity andwhile the slug is confined and held stationary by percussive forceapplied to the slug simultaneously cupping the inner end of the slug andcausing metal of the outer end of the slug to ex- Atru-de out of and beshaped by the Imouth of the die cavity onto the means for applying, andin a direction op osite to the application of, said force andp in,subsequently bevelling the cupped end, rounding the elongated end,andthreadin the outer surface of the blank thus forme.

CHARLES E. LYMAN.`

form a socket there-

